This invention relates generally to the construction of silos and silo doors. More particularly, the instant invention relates to an automatically openable silo door and a silo equipped with a plurality of automatic doors.
Argricultural silos are used to store a wide variety of agricultural products. Silage stored therewithin may be inputted interiorly of the silo through an upper door in the roof, and when it is desired to remove this silage it may be discharged therefrom through a plurality of conventional, vertically spaced apart silo orifices disposed on one side of the silo. The orifices are typically covered with some form of door which may be moved between open and closed positions where desired to discharge silage.
A plurality of prior art silo door systems are known. U.S. Pat. Nos. 2,367,720, issued to M. Goldbeck, 2,341,763, issued Feb. 15, 1944, issued to Z. Craine, and 952,876, issued Mar. 22, 1910, all show silo doors mounted to silo orifices through hinges whereby the doors may be completely moved out of the discharge opening. U.S. Pat. No. 2,068,972, issued to Bangert on Jan. 26, 1937, discloses a silo door adapted to be pivotally moved out of and away from a door opening. U.S. Pat. Nos. 1,106,662, 1,203,397, issued to C. Perkins; 1,387,751, issued to V. Bauder, on Aug. 16, 1921; and 1,811,486, issued to S. Anderson, on June 23, 1931; all disclose silo doors adapted to be secured to silo discharge orifices. U.S. Pat. No. 2,931,599, issued Apr. 5, 1960, discloses a door adapted for use with a pressurized aircraft cabin.
Also relevant is U.S. Pat. No. 3,709,345, issued to the same assignee as in the present case. Therein are depicted silo doors which are adapted to pivot outwardly from the silo discharge orifices in which they are received when in a closed position. A co-pending U.S. Pat. application, Ser. No. 610,453, filed Sept. 4, 1975, assigned to the same assignee as in the instant case and issued on Dec. 14, 1976 as U.S. Pat. No. 3,997,025 is also relevant to the silo door art.
Prior art silo doors are adapted to be opened through a plurality of conventional, usually manually operable schemes. For example, it is known to secure a door manually through the use of a simple latch mechanism. Moreover, offset hinge means have been provided whereby the door may be secured within the silo discharge orifice when in a closed position, and moved completely out of the orifice and away from it during unloading of the silo. Where a silo is to be unloaded the farmer need merely manually open the vertically spaced apart doors along the side of the silo one at a time depending upon the position of the internally disposed, silo unloading apparatus. Usually a ladder structure must be climbed by the farmer to reach the silo doors in order to manually open them during the unloading process. Examples of this type of ladder construction are shown in the aforementioned co-pending application, Ser. No. 610,453, filed Sept. 4, 1975, Group Art Unit 353, and in the aforementioned U.S. Pat. No. 3,709,345.
At present it is known to unload silos through the use of internally disposed, rotatable silo unloaders which have an element which rotates within the silo to pick up silage for subsequent discharge through a guide member which communicates outwardly through the silo door orifice. Silos of this type include a revolvable member usually having an auger of some form therewithin which rest upon silage internally of the silo and revolve about a circular path thereby picking up and discharging silage and progressively becoming lowered in the silo during the process of unloading. Raw material picked up by the rotatable member is delivered to the center of the apparatus and blown through the discharge chute out of the silage discharge opening. Known prior art silage unloaders constructed generally in this fashion are disclosed in U.S. Pat. Nos. 2,963,327, issued Dec. 6, 1960; 3,002,790, issued Oct. 3, 1961, to G. Chapman, and 3,531,059, issued Nov. 10, 1970. When silo unloaders of the type described are employed internally of the silo, it is normally the job of the operator to sequentially open the silo discharge doors at an appropriate time. If, for example, the doors are all opened at once, silage stored at lower levels within the silo will spoil or escape in a haphazard manner. On the other hand, even if the silo doors are sequentially manually opened it is often disadvantageous for the operator to climb to the appropriate position or to otherwise manipulate the silo door.